Much research and development on autonomous underwater vehicles (AUVs) has focused on larger vehicles driven by propellers (see for example “Trends in Biorobotic Autonomous Undersea Vehicles,” IEEE Journal of Oceanic Engineering, Vol. 30, No. 1, pp. 109-139, January 2005 by P. R. Bandyopadhyay, incorporated herein by reference).
Research and development has also focused on vehicles with undulatory body motions (see for example “An Efficient Swimming Machine,” Scientific American, Vol. 272, Issue 3, pp. 64-70, March 1995 by M. S. Triantafyllou et al., “The Geometric Mechanics of Undulatory Robotic Locomotion,” The International Journal of Robotics Research, Vol. 17, No. 7, pp. 683-701, July 1998 by J. Ostrowski et al., “Hydrodynamics of Fishlike Swimming,” Annual Review of Fluid Mechanics, Vol. 32, pp. 33-53, 2000 by M. S. Triantafyllou et al., “Nonlinear Control Methods for Planar Carangiform Robot Fish Locomotion,” Proceedings of the 2001 IEEE International Conference on Robotics and Automation, pp. 427-434, 2001 by K. A. Morgansen et al., and “Design and Dynamic Analysis of Fish Robot: PoTuna,” Proceedings of the 2004 IEEE International Conference on Robotics and Automation, pp. 4887-4892, April 2004 by E. Kim et al., each of which is incorporated herein by reference).
More recently, developments in the design and propulsion of biomimetic autonomous underwater vehicles (AUVs) have focused on boxfish as models (see for example “Biomimetric Micro Underwater Vehicle with Oscillating Fin Propulsion: System Design and Force Measurement,” Proceedings of the 2005 IEEE International Conference on Robotics and Automation, pp. 3312-3317, April 2005 by X. Deng et al., incorporated herein by reference). In this paper a biomimetic system concept design, fabrication details and experimental force measurements on prototype boxfish-inspired vehicles are presented.
While swimming mechanics in boxfish are well understood (e.g. routine swimming performance, maneuverability and stability, carapace hydrodynamics, drag and lift, and vortical flow self-correcting forces), little attention has been given to the functional design and operation of boxfish-inspired vehicles (see for example “Does A Rigid Body Limit Maneuverability?,” The Journal of Experimental Biology, Vol. 203, pp. 3391-3396, 2000 by J. A. Walker, “Boxfishes and Unusually Well-Controlled Autonomous Underwater Vehicles,” Physiological and Biological Zoology, Vol. 73, No. 6, pp. 663-671, 2000 by M. S. Gordon et al., “Boxfishes (Teleoste: Ostraciidae) As A Model System For Fishes Swimming With Many Fins: Kinematics,” The Journal of Experimental Biology, Vol. 204, pp. 1459-1471, 2001 by J. R. Hove et al., “Fish Functional Design and Swimming Performance,” Journal of Fish Biology, Vol. 65, pp. 1193-1222, 2004 by R. W. Blake, and “Evidence of Self-Correcting Spiral Flows in Swimming Boxfishes,” Bioinspiration & Biomimetrics, Vol. 3, 2008 by I. K. Bartol et al., each of which is incorporated herein by reference).
In particular, while boxfish-inspired vehicles have many potential advantages in operating in complex environments (e.g. high maneuverability and stability), limited battery life and payload capacities are likely functional disadvantages. In particular, boxfish employ undulatory median and paired fins during routine swimming which are characterized by high hydromechanical Froude efficiencies (≈0.9) at low forward speeds. However, current boxfish-inspired vehicles are propelled by a low aspect ratio, ‘plate-like’ caudal fin (ostraciiform tail) which can be shown to operate at a relatively low maximum Froude efficiency (≈0.5) and is mainly employed as a rudder for steering and in rapid swimming bouts (e.g. escape responses).